3. Will it help that I've never been arrested?
Sort of. Understand that your lack of a prior Sonoma County criminal record is usually not a sole basis to dismiss a current DUI case in Sonoma County or even to get a better plea deal. But of course, it is far better if you have a clean record, because those people who don't are typically exposed to increased penalties (like jail) in a new case depending on the number, nature, and recency of their prior convictions.
In rare cases, where the Santa Rosa District Attorney's office is wavering on a dismissal or an especially terrific plea deal, a defendant's clean prior criminal record, perhaps coupled with significant community or charitable history, etc, timely and properly presented by a defense attorney may encourage a desirable result.
The most helpful non-legal factors in obtaining a better resolution of a Sonoma County DUI case in court tend to be good driving before you were stopped, and cooperation with the police. But the best way to reduce or dismiss charges is for a Santa Rosa DUI defense lawyer to argue weaknesses in the District Attorney's case against you. Consult with a Sonoma County DUI lawyer about your specific case.